Since 1986 the Phoenix Epidemiology and Clinical Research Branch has been designated as the World Health Organization (WHO)Collaborating Center for Design, Methodology and Analysis of Epidemiological and Clinical Investigations in Diabetes. The purposes of the Center are to collaborate with WHO to implement the WHO/IDF action program on diabetes and to provide advice, consultation and collaboration with other investigators in the design, methodology and analysis of epidemiological and clinical studies of type 2 diabetes and its complications. The center assists in the development and application of standardized methods for epidemiological and clinical investigation and data analysis relating to the etiology and pathogenesis of type 2 diabetes and its complications. The Center advises in the design of new studies, and provides on-site assistance when necessary. The Center serves to train investigators from many parts of the world in diabetes epidemiology and clinical research. The center participated in the Consultation Group which has made the recently adopted WHO recommendations on the Definition, Diagnosis and Classification of Diabetes Mellitus and its Complications, and this year has trained investigators from Sierra Leone and the United Kingdom.